It is standard practice in the United States for broadcasters to insert into program material, at various points, a number of commercial messages of the program's sponsors. Many viewers find these messages to be an irritating interruption of their viewing pleasure.
Accordingly, many techniques have been devised in an effort to avoid being subjected to these commercial messages. One such technique is to merely mute the sound via, for example, a mute pushbutton on a remote control handunit. A remote control having such a mute function is known from the RCA CRK33 remote control transmitter handunit manufactured by Thomson Consumer Electronics, Inc., Indianapolis, Indiana. Unfortunately, muting the sound does not remove the video of the unwanted commercial message, and the viewer must watch the commercial in order to know when it has ended, and therefore, when the viewer can "unmute" the sound.
An improved sound muting technique is known from U.S. Pat. No. 3,870,956 (Wolff) issued 11 Mar. 1975. Wolff discloses a circuit to mute the sound of a television receiver for a predetermined time, at the end of which time the receiver sound circuitry is automatically unmuted. The circuitry of Wolff, however, does not affect the video, and thus a viewer is subjected to a series of silent commercial messages.
Of course, a viewer may simply tune to a second channel when a commercial message is displayed on the first tuned channel. A problem with this technique is that the viewer has no way of knowing when the commercial message on the first channel is finished. Consequently, the viewer may be late in returning to the first channel, and may miss a portion of the program he was watching.